Usher, Rihanna, Pitbull and Justin Bieber all have potentially summer-defining tunes currently loitering on the charts, but 2012’s most promising pieces of summer bubble gum come from new faces — an international smattering of boy bands and party girls from Canada, the U.K. and Sweden (a nation where pop music is taken with summertime seriousness all year round).

What makes a summer song The Song of the Summer? We’ve usually already heard it by April. It often leans toward the rhythms of hip-hop and R&B. It has a chorus that minivan-loads of tweenage girls can — and will — sing along to. Loudly. It can articulate sticky human emotions with a few gloriously melodic syllables, making you feel something deep without asking you to think too hard. Years later, it’s difficult to remember it existing outside of the summer when it arrived, and ironically, it becomes eternal because of that fact.

That’s why we love to argue about The Song of the Summer, even if some think the debate has become a media contrivance. A great pop song is a great pop song, regardless of the heat index, right? It’s not like Beyonce wrote “Crazy in Love” on a boogie board.

But we can’t help ourselves. Last year, perhaps in an attempt to be a little more scientific about it, Billboard published a weekly “Songs of the Summer” chart, which ranked hits by how well they performed on the regular Hot 100 singles chart between June 11 and Sept. 8.

More useful: Billboard’s lists of the biggest hits from summers past. Rihanna and Katy Perry both made chart debuts with breakout summer singles, but most of the past decade’s summertime hitmakers seemed to vanish after Labor Day. (Nina Sky, we miss you!)

Even if summer isn’t starmaking season, it still provides an increasingly rare communal moment for the rest of us. Windows are rolled down, volume knobs are cranked up. These songs drift through the air and braid themselves into our memory. We associate them with the cold splosh of SPF 30 on our backs, the smell of Kingsford briquettes, the taste of sugar-dusted-deep-fried-everything.

Which song will most remind us of the summer that’s about to happen? Here are five leading hopefuls.

Perhaps you’re one of the 9 million YouTubers who have watched the Harvard University baseball team dance to this one during a van ride to an away game. A few months before that video went viral, Carly Rae Jepsen was touring across her native Canada in her own “soccer mom van,” opening for ’90s survivalist boy band Hanson.

“Show by show, we’d start to sneak a box of merch onto the Hanson tour bus so we could get away with a little more leg space,” Jepsen says. “At the same time, I was negotiating the deal with Scooter Braun.”

Braun is the guy who discovered Justin Bieber, who actually alerted Braun to Jepsen’s existence when he heard “Call Me Maybe” on Canadian radio. Now, Jepsen is signed to Braun’s Schoolboy Records and “Call Me Maybe” has risen to the summit of the iTunes singles chart.

Alongside swooping strings and a disco beat that thumps like an anxious heart, Jepsen serves up the song’s chorus while staring at her shoes: “Hey, I just met you / And this is crazy / But here’s my number / So call me, maybe?” In today’s hyper-sexualized popscape, the song’s appeal feels obvious. Here’s a 26-year-old singing about the butterflies that usually quit flapping after adolescence.

“I think my personality is a little more coy rather than aggressive when it comes to love,” says Jepsen. “There are often times when you meet somebody, and there’s some chemistry, but you let it lie. . . . It’s scary to approach somebody.”

This 21-year-old British singer topped the U.K. charts in May with a vinegar-doused track called “R.I.P.,” but her entry to the summer jam sweepstakes is all sugar and caffeine. And a little liquor, too.

“When the sun sets baby, on the avenue / I get that drunk sex feeling, yeah, when I’m with you,” Ora sings on “How We Do (Party),” her first U.S. single. After the boozy refrain, she cribs a profane hook from a Notorious B.I.G. song whose title we can’t print here.

Funny how it all sounds so innocent. As an acoustic guitar strums inoffensively in the background, Ora sings about warding off her hangover by falling in love with the guy passed out on the floor. It’s sweetly disorienting — like a Ke$ha lyric trapped in a Miley Cyrus melody.

Jay-Z is into it. The hip-hop superstar signed Ora to his Roc Nation imprint back in 2009 and booked her to perform alongside Pearl Jam, Skrillex, Janelle Monae and others at “Made in America,” the marvelously motley music festival he’s hosting in Philadelphia over Labor Day weekend. By then it should be clear if “How We Do (Party)” has graduated to Song of The Summer status.

Last summer, two British-Irish boy bands each released pop singles that made them seem as different as two British-Irish boy bands could be. A year later, across the Atlantic, those tunes have a lot in common. They’re impossible to avoid.

The Wanted, five singers assembled in 2009 after a mass audition, carry themselves more like a young man band than a boy band, thanks to “Glad You Came.” The song’s club-friendly beat helped it peak at No. 3 on Billboard, and its smart, understated melodies made these guys seem like they aspire to be more than just adorable.

One Direction, on the other hand, epitomizes adorable. Since finishing third on “X-Factor,” (England’s version of “American Idol”), the shaggy quintet has become ubiquitous, too. They turned down an invitation to perform at the White House Easter Egg Roll and accepted an invitation to sing on “Saturday Night Live,” where their performance of “What Makes You Beautiful” had all the charisma of a herd of deer in headlights. But the song itself remains an unimpeachable puppy love carpet bombing.

This vivacious Stockholm duo is currently living out of suitcases in London where the gigs have been steady and the crowds have been eager to shout along to “I Love It,” the most exhilarating 2 1/2 minutes of pop music released this year.

“I put your [things] into a bag and kicked it down the stairs,” the pair sing-shouts. “I crashed my car into the bridge! I don’t care! I love it!”

Drum machines thundering, synthesizers pealing, the song brilliantly distills the nihilistic ecstasy of a post-breakup freakout. “It’s about that point when you think, ‘It’s good for me to move on and I’m pretty awesome,’” says Caroline Hjelt, 24. She and Aino Jawo, 25, say they’re glad their empowerment anthem is making ripples on the American bandwidth. In their eyes, there’s never been a better time to be a wannabe pop star. “Now, it seems like everything is pop,” says Jawo. “We can mix all of these genres together and call it pop. I think that’s wonderful.”

They hope to join a lineage of Swedes dedicated to the craft — from Abba, to Roxette, to Ace of Base, to Robyn. “In Sweden, pop music is very respected,” says Hjelt. “Everyone listens to it, from my little sister to my grandma. It’s a very big part of Swedish culture.”

But that doesn’t mean the duo isn’t dreaming beyond Stockholm, the blogosphere and the summer of 2012.

Says Jawo: “We want to be the new Prince!”

Summer Songs, 2002-2011: Check our Chris Richards’ list of the best summer jams of the last decade, or listen to his Spotify playlist, above. Spotify is free, and you can sign up through Facebook. Some songs may contain inappropriate language.

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